JP3052910B2 - Magnetoresistive magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head used in a magnetic disk drive.

[0002]

2. Description of the Related Art In a magnetoresistive head used in a magnetic disk drive, in order to make the magnetoresistive film function stably as a reproducing head, the magnetoresistive film is moved horizontally and vertically with respect to the magnetoresistive film. It is necessary to apply a bias magnetic field in both directions.

The lateral bias magnetic field is a bias magnetic field required to shift the operating point of the reproducing head to the most linear range of the RH characteristic curve (magnetoresistance effect curve), and the linearity of the reproducing output is reduced. It is intended to keep. This lateral bias magnetic field is a magnetic field perpendicular to the recording surface of the magnetic recording medium, and is applied in a direction parallel to the surface of the magnetoresistive film, so that the shunt bias method (the shunt conductor between the magnetoresistive element and the shunt conductor) is applied. A current is applied to both, and a bias is applied to the magnetoresistive element by a magnetic field generated from the shunt conductor, and a SAL bias method (a soft magnetic adjacent layer bias method:
A method in which a current is applied to both the magnetoresistive element and the soft magnetic adjacent layer, and a bias is applied to the magnetoresistive element with a magnetic field generated from the soft magnetic adjacent layer).

The longitudinal bias magnetic field is a magnetic field applied in parallel to the recording surface of the magnetic recording medium and in parallel with the longitudinal direction of the magnetoresistive film. It has a function of suppressing Barkhausen noise generated by magnetic domain action.

[0005] Conventionally, two means have been used for applying a longitudinal bias magnetic field. One of them is
For example, as disclosed in Japanese Patent Application Laid-Open No. 62-40610, this is a means for using an antiferromagnetic film such as an iron-manganese (FeMn) alloy to exchange-couple with a magnetoresistive effect film. Discloses cobalt-chromium-platinum (CoCr) as disclosed in JP-A-2-220213.
This is a means for ferromagnetically coupling or magnetostatically coupling a hard magnetic film having a high coercive force such as Pt) alloy and a magnetoresistive film which is a soft magnetic film.

[0006]

Among the above-described conventional magnetoresistive heads, the former using the antiferromagnetic film as the means for applying the longitudinal bias magnetic field uses the latter hard magnetic film. Although a large reproduction output can be obtained as compared with the conventional one, there is a problem that Barkhausen noise cannot be sufficiently suppressed. Also, with the increase in the density of the magnetic disk drive, the read TW
Since the (effective reading track width) is reduced, there is also a problem that the reproduction output is reduced and Barkhausen noise is increased.

An object of the present invention is to provide a magnetoresistive head having the above-described means for applying a lateral bias magnetic field and a longitudinal bias magnetic field, which can suppress Barkhausen noise of the magnetoresistive film. Moreover, it is an object of the present invention to provide a magnetoresistive head capable of obtaining a high reproduction output.

[0008]

According to a first aspect of the present invention, there is provided a magnetoresistive head having a lower magnetic shield film of a nickel-iron alloy formed on a non-magnetic substrate of aluminum-titanium-carbon. Forming a first read gap of an aluminum oxide film on the magnetic shield film, forming a soft magnetic adjacent layer film of a cobalt-zirconium-molybdenum alloy on a central portion of the first read gap, A non-magnetic conductive film of tantalum is formed on the adjacent layer film, a magnetoresistive film of a nickel-iron alloy is formed on the non-magnetic conductive film, and a gap equal to or more than a read track width is formed on the magnetoresistive film. To form a pair of nickel-maganium alloy vertical bias effect films having a width W. The vertical bias effect film and the first reproducing gap correspond to the pair of vertical bias effect films. Said forming a pair of electrodes of the same interval as the read track width, a second read gap oxide aluminum is formed on said pair of electrodes on the end,
A magneto-resistance effect type magnetic head using a reproducing element in which a nickel-iron alloy upper magnetic shield film is formed on the second reproducing gap as a reproducing head, and using a thin film head as a recording head. The width W of each of the pair of longitudinal bias effect films is set to 2.0 μm to 4.0 μm. In particular, each outer end of the pair of longitudinal bias effect films is connected to the outer end of the magnetoresistive film. In this case, the distance between the pair of vertical bias effect films is equal to the distance between the pair of electrodes.

In a second magnetoresistive head according to the present invention, a nickel-iron alloy lower magnetic shield film is formed on an aluminum-titanium-carbon nonmagnetic substrate, and the lower magnetic shield film is formed on the lower magnetic shield film. A first read gap of an aluminum oxide film is formed, and a pair of nickel-maganium alloy longitudinal bias effect films having a width W is provided on a central portion of the first read gap at a distance equal to or greater than a read track width. Forming a nickel-iron alloy magnetoresistive effect film on the pair of longitudinal bias effect films; forming a tantalum nonmagnetic conductive film on the magnetoresistive effect film; Forming a soft magnetic adjacent layer film of a cobalt-zirconium-molybdenum alloy on the soft magnetic adjacent layer film and the pair of longitudinal bias effect films on the edge of the first read gap. Forming a pair of electrodes at the same interval as the lead track width, forming a second reproducing gap of aluminum oxide on the pair of electrodes, and forming a nickel-iron on the second reproducing gap. Using the read element with the upper magnetic shield film of alloy as the read head,
A magnetoresistive magnetic head using a thin film head as a recording head, wherein each of the pair of longitudinal bias effect films has a width W of 2.0 μm to 4.0 μm. The outer ends of the pair of longitudinal bias effect films are made to coincide with the outer ends of the magnetoresistive effect film, or the interval between the pair of longitudinal bias effect films is equal to the interval between the pair of electrodes. .

[0010]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a reproducing section of a first embodiment of a magnetoresistive magnetic head according to the present invention, and FIG. 5 is a width (exchange coupling width) of a longitudinal bias effect film in the embodiment of FIG.
FIG. 6 is a characteristic diagram showing the relationship between the width of the vertical bias effect film (exchange coupling width) and the wiggle in the embodiment of FIG.

FIG. 1 shows an embodiment in which a nonmagnetic substrate 1 of aluminum-titanium-carbon (AlTiC) is provided.
A lower magnetic shield film 2 of a nickel-iron (NiFe) alloy having a thickness of 2000 nm is formed by electroplating, and an aluminum oxide (Al ₂ O ₃ ) film (reproduction gap) 3 having a thickness of 70 nm is sputtered thereon. It is formed by the method.

Further, a soft magnetic adjacent layer film (SAL film) 4 of a cobalt-zirconium-molybdenum (CoZrMo) alloy having a thickness of 27 nm is formed on the central portion of the reproducing gap 3.
A nonmagnetic conductive film 5 of tantalum (Ta) having a thickness of 10 nm on the SAL film 4 and a nonmagnetic conductive film 5
A magnetoresistive film 6 of a nickel-iron (NiFe) alloy having a thickness of 20 nm is formed by a sputtering method.

Further, a pair of nickel-maganium (NiMn) alloy vertical bias effect films 7 having a width W are formed to a film thickness of 50 nm on the magnetoresistive effect film 6 at intervals larger than the read track width V. A 100 nm-thick gold (Au) film on both ends of the vertical bias effect film 7 and the reproducing gap 3.
Are formed by the sputtering method. (The interval V between the pair of electrodes 8 is the same as the read track width.) Further, a reproducing gap 9 of aluminum oxide (Al ₂ O ₃ ) having a thickness of 90 nm is formed on the electrodes 8 by a sputtering method. An upper magnetic shield film 10 of a 3000 nm thick nickel-iron (NiFe) alloy is formed thereon by electroplating.

Using the reproducing element constructed as described above as a reproducing head, a conventional thin film head is used as a recording head to form a magnetoresistive head.

The width W of the longitudinal bias effect film 7 (which is called an exchange coupling width) affects Barkhausen noise of the magnetoresistive head. In order to confirm the situation, in the configuration of FIG. 1, both outer ends of the vertical bias effect film 7 are made to coincide with the outer ends of the magnetoresistive film 6, and the width W of the vertical bias effect film 7 is set to 1.5 μm · 2. 0.0 μm
Prototypes of 3.0 μm, 4.0 μm, 5.5 μm, and 6.5 μm magnetoresistive effect type magnetic heads, and asym variations of the values representative of their Barkhausen noise (1000 write operations at a specific frequency) The reading was repeated, the asymmetry of the output voltage waveform was obtained, and the difference between the maximum value and the minimum value was obtained: the waveform asymmetry fluctuation) was measured. FIG. 5 is a characteristic diagram showing the result.

As is apparent from FIG. 5, the width (exchange coupling width) W of the vertical bias effect film 7 is 2.0 μm and 3.0 μm.
When the width W of the longitudinal bias effect film 7 is 1.5 μm, 5.5 μm and 6.5 μm, the Asym fluctuation is 13 to 18% when m and 4.0 μm. It is. Therefore, it can be understood that by setting the width W of the vertical bias effect film 7 to 2.0 μm to 4.0 μm, disturbance of the magnetic domains of the magnetoresistive effect film 6 can be reduced and Barkhausen noise can be suppressed.

With respect to the above prototype, a wiggle (10% at a specific frequency) which is another means of detecting Barkhausen noise is used.
FIG. 6 shows the result of measuring the average value of the output voltage and the standard deviation (the ratio of the standard deviation to the output voltage) when writing and reading are repeated 0 times.

In this case, similarly to FIG. 5, the width W of the vertical bias effect film 7 is 2.0 μm, 3.0 μm, and 4.0.
In the case of μm, the wiggle is 1.0% or less, but when the width W of the longitudinal bias effect film 7 is 1.5 μm, 5.5 μm, and 6.5 μm, the wiggle is 1.7 to 2.5%. . Therefore, the width W of the vertical bias effect film 7 is set to 2.0 μm or less.
It can be seen that by setting the thickness to 4.0 μm, the wiggle becomes small and Barkhausen noise can be suppressed.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

The structure of this embodiment is basically the same as that of the embodiment of FIG. 1, except that the SAL film 14, the nonmagnetic conductive film 15, the magnetoresistive film 16, and the longitudinal bias effect film 17 which are intermediate layers are formed. Are different in the stacking order. The upper and lower lower magnetic shield films 12 and the read gap 13
The order of lamination of the electrode 18, the reproducing gap 19, and the upper magnetic shield film 20, and their thicknesses are the same as those in the embodiment of FIG.

The stacking sequence of the SAL film 14, the non-magnetic conductive film 15, the magnetoresistive effect film 16, and the vertical bias effect film 17 is as follows: first, a pair of vertical bias effect films 17 are formed on the reproducing gap 13; The magnetoresistive film 16, the nonmagnetic conductive film 15, and the SAL film 14 are formed thereon in this order. The thickness of each of these films is the same as in the embodiment. The width W of the two longitudinal bias effect films 17 is 2.0 μm to 4.0 μm.

With this configuration, the same operation and effect as in the embodiment of FIG. 1 can be obtained.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

The structure of this embodiment is such that the SAL film 24, the non-magnetic conductive film 25, and the magnetic resistance are provided between the upper and lower lower magnetic shield films 22 and the reproducing gap 23, and between the electrode 28, the reproducing gap 29 and the upper magnetic shield film 30. Although the effect film 26 and the vertical bias effect film 27 are stacked in the same stacking order as the embodiment of FIG. 1, the configuration of the vertical bias effect film 27 is slightly different. That is, 1
The interval between the pair of vertical bias effect films 27 is made equal to the interval V between the electrodes 8, and their width W is set to 2.0 μm to 4.0 μm. Therefore, the outer end of the vertical bias effect film 27 does not coincide with the outer end of the magnetoresistive effect film 26, but is inside them. The width of the pair of electrodes 28 matches the width of the lead track.

In this embodiment, the same operation and effect as in the embodiment of FIG. 1 can be obtained.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

The structure of this embodiment is such that all the layers are stacked in the same stacking order as the embodiment of FIG. 2, but the structure of the vertical bias effect film 37 is the same as that of the embodiment of FIG. is there. That is, the interval between the two vertical bias effect films 37 is made equal to the interval V between the electrodes 8 as in the embodiment of FIG. 3, and the width W thereof is set to 2.0 μm to 4.0 μm. Therefore, the outer end of the vertical bias effect film 37 does not coincide with the outer end of the magnetoresistive effect film 36 but is inside them. The width of the pair of electrodes 38 matches the width of the lead track.

In this embodiment, the same operation and effect as in the embodiment of FIG. 1 can be obtained.

[0030]

As described above, in the magneto-resistance effect type magnetic head of the present invention, the SAL film, the non-magnetic conductive film and the magnetic resistance are formed between the upper and lower reproducing gaps in order to form the reproducing element of the reproducing head. When the effect film, the pair of longitudinal bias effect films, and the pair of electrodes are stacked, the width of the pair of longitudinal bias effect films is set to 2.0 μm to 4.0 μm to reduce disturbance of the magnetic domains of the magnetoresistive effect film. Thus, there is an effect that Barkhausen noise can be suppressed, so that a magnetoresistive head having a stable and high reproduction output can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a reproducing unit according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a reproducing unit according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a reproducing unit according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a reproducing unit according to a fourth embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a width of a vertical bias effect film and an asym variation rate in the embodiment of FIG. 1;

FIG. 6 is a characteristic diagram showing a relationship between a width of a vertical bias effect film and a wiggle in the embodiment of FIG. 1;

[Explanation of symbols]

 1.11.12.31 Non-magnetic substrate 2.12.22.32 Lower magnetic shield film 3.13.23.33 Reproduction gap 4.14.24.34 SAL film 5.15.25.35 Non-magnetic conductive film 6.16.26.36 Magnetoresistive film 7.17.27.37 Longitudinal bias effect film 8.18.28.38 Electrode 9.19.29.39 Reproduction gap 10.20.30.40 Upper magnetic shield film

Claims (6)

(57) [Claims] 1. A nickel-iron alloy lower magnetic shield film is formed on an aluminum-titanium-carbon nonmagnetic substrate, and a first reproduction gap of an aluminum oxide film is formed on the lower magnetic shield film. Forming a soft magnetic adjacent layer film of a cobalt-zirconium-molybdenum alloy on a central portion of the first read gap, forming a non-magnetic conductive film of tantalum on the soft magnetic adjacent layer film, A nickel-iron alloy magnetoresistive film is formed on the magnetic conductive film, and a pair of nickel-maggan alloy longitudinal bias effect films having a width W is provided on the magnetoresistive film with an interval equal to or greater than the lead track width. And forming a pair of electrodes at the same interval as the read track width on the longitudinal bias effect film and the end of the first read gap corresponding to the pair of longitudinal bias effect films. A reproducing element having a second reproducing gap of aluminum oxide formed on the pair of electrodes and a nickel-iron alloy upper magnetic shield film formed on the second reproducing gap; Used as
A magnetoresistive head using a thin film head as a recording head, wherein each of the pair of longitudinal bias effect films has a width W of 2.0.
A magnetoresistance effect type magnetic head having a thickness of from μm to 4.0 μm. 2. The magnetoresistive head according to claim 1, wherein each outer end of the pair of longitudinal bias effect films is made to coincide with the outer end of the magnetoresistive effect film. 3. The magnetoresistive head according to claim 1, wherein the interval between the pair of longitudinal bias effect films is equal to the interval between the pair of electrodes. 4. A nickel-iron alloy lower magnetic shield film is formed on an aluminum-titanium-carbon nonmagnetic substrate, and a first reproduction gap of an aluminum oxide film is formed on the lower magnetic shield film. Forming a pair of nickel-maganium alloy vertical bias effect films having a width W at intervals above the central portion of the first read gap with a width equal to or greater than the read track width; A magnetoresistive film of a nickel-iron alloy is formed thereon, a nonmagnetic conductive film of tantalum is formed on the magnetoresistive film, and cobalt-zirconium- is formed on the nonmagnetic conductive film.
Forming a soft magnetic adjacent layer film of a molybdenum alloy, and having the same distance as the read track width corresponding to the pair of longitudinal bias effect films on the soft magnetic adjacent layer film and the end of the first read gap; Were formed, a second reproducing gap of aluminum oxide was formed on the pair of electrodes, and an upper magnetic shield film of a nickel-iron alloy was formed on the second reproducing gap. A magnetoresistive head using a reproducing element as a reproducing head and a thin film head as a recording head, wherein each of the pair of longitudinal bias effect films has a width W of 2.0.
A magnetoresistance effect type magnetic head having a thickness of from μm to 4.0 μm. 5. The magnetoresistive head according to claim 4, wherein each outer end of the pair of longitudinal bias effect films is made to coincide with the outer end of the magnetoresistive effect film. 6. The magnetoresistive head according to claim 4, wherein the interval between the pair of longitudinal bias effect films is equal to the interval between the pair of electrodes.